A forum for reverse engineering, OS internals and malware analysis 

Forum for analysis and discussion about malware.
 #30945  by rusl
 Tue Oct 24, 2017 10:29 pm
579fd8a0385482fb4c789561a30b09f25671e86422f40ef5cca2036b28f99648
this is а DLL:
Code: Select all
rundll32 579fd8a0385482fb4c789561a30b09f25671e86422f40ef5cca2036b28f99648.dll, #1 10
10 - time (in minutes) before the system restarts
 #30949  by EP_X0FF
 Thu Oct 26, 2017 3:56 am
New trend of home made analysts - post sandbox log photoshoped as "analysis".

What attract my attention here is part about Tcb privilege adjustment.

Image

As author of this collage likely don't know that this privilege is not available in default configuration for windoze "admins" and probably also doesn't know what it does and for what purpose it even exist.

So I downloaded this trash in expectation of some "magic". To get payload dll without catching it on disk, put dropper into ollydbg and set breakpoint on NtCreateFile, once it hit with "\??\C:\windows\infpub.dat" inspect process virtual memory and dump region with dll inside.

Privileges adjusted just right in first subroutine of "payload main" which is first exported ordinal.
Code: Select all
.100078BB: 68F8160110                     push         0100116F8 ;'SeShutdownPrivilege
.100078C0: A3907B0110                     mov          [010017B90],eax
.100078C5: 33F6                           xor          esi,esi
.100078C7: E8F9030000                     call        .010007CC5 --↓2'AdjustPrivilegeProc
.100078CC: 85C0                           test         eax,eax
.100078CE: 7401                           jz          .0100078D1 --↓3
.100078D0: 46                             inc          esi
.100078D1: 6820170110                    3push         010011720 ;'SeDebugPrivige
.100078D6: E8EA030000                     call        .010007CC5 --↓2'AdjustPrivilegeProc
.100078DB: 85C0                           test         eax,eax
.100078DD: 7403                           jz          .0100078E2 --↓5
.100078DF: 83CE02                         or           esi,2
.100078E2: 68D8160110                    5push         0100116D8 ;'SeTcbPrivilege
.100078E7: E8D9030000                     call        .010007CC5 --↓2'AdjustPrivilegeProc
.100078EC: 85C0                           test         eax,eax
.100078EE: 7403                           jz          .0100078F3 --↓7
.100078F0: 83CE04                         or           esi,4
.100078F3: 8935C07B0110                  7mov          [010017BC0],esi'remember set of adjusted privileges
TCB required for setting SessionId value in token impersonation operations. If you look code more you will find this part too (with check if privilege was adjusted via looking up global variable).

No magic here, set of ridiculous shit copy-paste code where authors not really understand why they need some parts as well as these who "analyse" it. Also ridiculous use of DiskCryptor, how fuck lol is that just because initially it is supposed to be part of malware rootkit self defense.
 #30984  by rever_ser
 Sat Nov 11, 2017 6:51 am
Antelox wrote:Here you go.

BR,

Antelox
hi! what is the password of the "samples.zip" for extract?
 #30991  by Antelox
 Sun Nov 12, 2017 3:53 pm
rever_ser wrote:
Antelox wrote:Here you go.

BR,

Antelox
hi! what is the password of the "samples.zip" for extract?
infected...

BR,

Antelox